This commentary opens with an exposition of Alison Stone's novel reading of Irigaray's philosophy of sexual difference. This reading proposes that Irigaray's philosophy of sexual difference is a realist essentialism that reposes upon a general ontology of natural rhythm whose philosophical source is the nature philosophy of Schelling. Distinguishing between two accounts, a rhythmic account of natural, human sex difference and a relational account of cultivatable human, sexual difference, Stone's book unites these accounts to provide a comprehensive reading of Irigaray's philosophy of sexual difference. This article raises questions about the content of this new reading. The commentary asks whether and to what extent the rhythmic account of sex difference is established independently of a prior nonrhythmic or more conventional, biological notion of sex difference. It questions the classification of rhythmic processes that are purportedly differentiated by sex and offers a note of skepticism about the comparative classifications of reproductive and sexual impulses by sex. Finally, it treats the work's metaphysics of expression and tendency, inspired by Schelling's metaphysics, so as to inquire into its utility. The suggestion is that the value of this metaphysics may be undermined by the epistemological difficulty of distinguishing between a suppressed tendency and an absent one. The conclusion identifies this metaphysics of expression as a serious point of divergence between Stone's thought on sexuality and that of one of her interlocutors in the text, Judith Butler.